1. Field of the Invention
The present invention relates method and apparatus for data encryption. More specifically, the present invention relates to a method and apparatus for encrypting analog data while minimizing data loss.
2. Background of the Invention
The ability to securely transmit information between two locations is of paramount importance in today's communication systems. Before the invention of digital transmission methods, analog transmission was commonplace. However, today's communication systems rely almost exclusively on transmitting information digitally. Digital transmission has become commonplace because it provides optimal accuracy and security. While it is optimal for many applications, digital transmission also creates a major disadvantage. In order to convert an analog signal into the digital domain, analog information must be sampled in accordance with, for example, the Nyquist sampling theorem. According to this theorem, an analog signal should be sampled at least twice the frequency of the analog signal. Therefore, transmitting information digitally requires the necessary bandwidth to be a function of the sampling frequency, the number of bits per sample, and the bandwidth efficiency of the modulator. For many systems, digital transmission can drastically increase the bandwidth that is required. In certain applications where bandwidth is limited, analog transmission can be more efficient. However, because of the increased accuracy and encryption ability afforded by digital transmission, current secure communication systems have not focused on securely transmitting data in the analog domain.
Another drawback of digital systems is their reliance on data compression. A typical example of this can be described with respect to a DVD player. The data on a DVD is in a highly compressed digital format. When a DVD disk is read by a DVD player, the player processes the compressed digital information and expands it into a visual image. However, during the process of expanding the information to form an image, some information is lost. In the case of a DVD player, the loss of information cannot be detected by the human eye. However, in applications where it is desirable to recover transmitted information completely, this would be disadvantageous.
A continuing need exists for improved methods and apparatus that can transmit analog data securely while minimizing the distortion of information.